Cant Start Wont Start!

[Louie C]

Having problems starting my S2 Avant

Having only owned it for a few months I noticed that every now and again on start up it wouldnt turn or fire as quickly as usual. I hoped it wasn't anything to worry about but over the weeks it happened more often!
Worst case being last week when it almost seemed like there was no power from the battery, didnt even try and turn and then was followed by what sounded like a buzzin feedback sound from behind the dash, then after a second that turned into the click click clickin you get when trying to start a car with a dead battery?..... left it for 5 mins then it just about turned and started up?

Drove it for a while and then when I got home I tried starting it straight after I parked up.... nothing, click click click, not even a turn

Car came with a GSF batt that had marker penned 'POOR' in yellow on it!) the GSF batt was checked and aparently 'unservicable' so I bought a Bosch silver S5.
Guess what?? Car still wont start and seems to still be having the same problem

Im sorry guys but I'm not that great with mechanical/elecrical stuff and I've tried looking at other threads with starting problems, I'm hoping this is something simple.

Louis

[SteveH]

If you've now got a known good battery, start checking your earthing points and alternator output.

[piotr]

check how much is your alternator charging.do the test with multimiter under the load with all lights,heated window etc.sitched on and then check readings again witch everything off.next thing to suspect is starter motor is giving up.did the engine turned over nice and quick straight after you fitted new battery?let us know your readings.i agree to earthing points.if all above will become all good you will have to performe battery drain check.